Heavy Metal Removal from Wastewater

The application of natural zeolites in heavy metal removal is described now. The methodology consists of the development of a process for heavy metal removal from wastewater using dynamic ion exchange in natural zeolite columns [38,53], 

FIGURE 7.12 Laboratory assembled modular canister setup composed of (a) ionic exchange column, (b) pump, (c) inlet valve, (d) elbow, (e) T connection, and (f) column valve. 

The mineralogical phase composition of the sample SW [86] (in wt %) is 90% 5% clinoptilolite and 10% 5% others, which include montmorillonite (2-10 wt %), quartz (1-5 wt %), calcite (1-6 wt %), feldspars (0-1 wt %), magnetite (0-1 wt %), and volcanic glass (3-6 wt %). Employing this sample and a pure clinoptilolite, whose TCEC fluctuates between 2.0-2.2 mequiv/g depending on the Si/Al relation of the clinoptilolite monocrystal, it is possible to indirectly evaluate the total cation-exchange capacity of the sample SW as follows  

The direct experimental evaluation of the TCEC of the natural SW clinoptilolite sample was carried out with the help of a methodology previously described, which resulted in the measurement of 

The Physical Chemistry of Materials Energy and Environmental Applications 

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Chemical Oxidation. Chemical oxidation can be appHed ia iadustrial wastewater pretreatment for reduction of toxicity, to oxidize metal complexes to enhance heavy metals removal from wastewaters, or as a posttreatment for toxicity reduction or priority pollutant removal. 

Biosorption is a process that utilizes biological materials as adsorbents [Volesky, 1994], and this method has been studied by several researchers as an alternative technique to conventional methods for heavy metal removal from wastewater. 

In a separate study, Igwe and Abia46 determined the equilibrium adsorption isotherms of Cd(II), Pb(II), and Zn(II) ions and detoxification of wastewater using unmodified and ethylenediamine tetraacetic acid (EDTA)-modified maize husks as a biosorbent. This study established that maize husks are excellent adsorbents for the removal of these metal ions, with the amount of metal ions adsorbed increasing as the initial concentrations increased. The study further established that EDTA modification of maize husks enhances the adsorption capacity of maize husks, which is attributed to the chelating ability of EDTA. Therefore, this study demonstrates that maize husks, which are generally considered as biomass waste, may be used as adsorbents for heavy metal removal from wastewater streams from various industries and would therefore find application in various parts of the world where development is closely tied to affordable cost as well as environmental cleanliness.46... 

Iron (III) hydroxide waste Especially for heavy metals removal from wastewater, iron (III) hydroxide waste and waste slurry from the fertilizer industry, xanthate, rice husk, carbon, and coconut shell have been studied and can be considered as alternatives. 

For designing a canister system for heavy metal removal (see Figure 7.12) [38,53], a simple phenomenological description of dynamic ion exchange in zeolite bed reactors was worked out, which allows for the design of modular canister ion-exchange bed reactors for applications in heavy metal removal from wastewater. 

Kislik V and Eyal A. Heavy metals removal from wastewaters of phosphoric acid production. A comparison of hybrid Uquid membrane (HLM) and aqueous hybrid liquid membrane (AHLM) technologies. In Proceedings of the Conference on Membrane in Drinking and Industrial Water Production, 2000 1 503-514. 

Dithiocarbamates have been covered in CCC (1987),378 in a comprehensive early review (together with xanthates)379 and in a book.380 They continue to be extensively used and much interesting novel chemistry has been reported since. Several reviews on dithiocarbamates cover the electro-chemistry, photoelectron spectroscopy, analytical applications of dithiocarbamates (e.g., for the determination of metals in foodstuff, water and environmental samples and the analysis of dithiocarbamate pesticides),383-386 their use as NO trapping agents,387-389 or in the heavy-metal removal from wastewaters.390... 

Mehta SK, Gaur JP (2005) Use of algae for removing heavy metal ions from wastewater progress and prospects. Grit Rev Biotechnol 25 113... 

Ngah, W.S.W. and Hanafiah, M.A.K.M., Removal of heavy metal ions from wastewater by chemically modified plant wastes as adsorbents A review, Bioresource Technology, 99, 3935-3948, 2008. 

Heavy) metals recovery from wastewater Removal of organic contaminants from wastewater... 

C. Blocher, J. Dorda, V. Mavrov, H. Chmiel, N. K. Lazaridis, and K. A. Matis, Hybrid flotation— membrane filtration process for the removal of heavy metal ions from wastewater. Water Research 37, 4018-1026 (2003). 

Hua M., Zhang S., Pan B., Zhang W., Lv L., and Zhang Q., Heavy metal removal from water/wastewater by nanosized metal oxides A review, J. Hazard. Mater. 211-212, 317, 2012. 

Cation exchange capacities ranged from 3.6 to 4.3 meq/g for pure zeolites and from 2.0 to 2.5 meq/g for zeolites containing residual fly ash. They showed that pure zeolites are suitable for the removal of ammonium and heavy metal ions from wastewater. 

Le, X. T., P. Viel, A. Sorin, P. Jegou, S. Palacin. Electrochemical behavior of polyacrylic acid coated gold electrodes An application to remove heavy metal ions from wastewater. Electrochim. Acta 54, 2009 6089-6093. 

Ion exchange is a means of removing cations or anions from solution onto a solid resin, which can be regenerated by treatment with acids, bases, or salts. The greatest use of ion exchange in hazardous waste treatment is for the removal of low levels of heavy metal ions from wastewater ... 

Fu F, Wang Q (2011) Removal of heavy metal ions from wastewaters a review. J Environ Manage 92(3) 407-418... 

Li S, Yue X, Jing Y, Bai S, Dai Z (2011) Fabrication of zonal thiol-functionalized sUica nanofibers for removal of heavy metal ions from wastewater. Colloid Surf A 380(l-3) 229-233, doi http //dx.doi.Org/10.1016/j.colsurfa.2011.02.027... 

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